1. Field of the Invention
The present invention relates to a machining center, and, more particularly, to an air driven spindle assembly insertable into a machining center.
2. Description of the Related Art
The abbreviation “CNC” stands for computer numerical control, and refers specifically to a computer “controller” that reads coded instructions and uses them to direct the driving of a machine tool. The machine tool may be a powered mechanical device used to fabricate components by the selective removal of material. A CNC machine may use interpolation of a cutting tool in the working envelope of the machine. The operating parameters of the CNC can be altered by way of software updates and instructions.
The CNC machines were preceded by NC (Numerically Controlled) machines, which were hardwired and their operating parameters were inflexible. NC machines were developed in the late 1940s and early 1950s. The first CNC systems used NC style hardware, and the computer was used for tool compensation calculations and sometimes for editing of the coded instructions.
Punched tape was used by some NC machines and continued to be used as a medium for transferring coded instructions into the controller for many years after 1950, until it was superseded by RS-232 communication schemes, floppy disks, and now networked systems.
The introduction of CNC machines radically changed the machining industry. Complex curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action have been dramatically reduced.
The increased automation of manufacturing processes with CNC machining, have yielded considerable improvements in the consistency and quality of the parts machined thereby. In a production environment, a series of CNC machines may be combined into one station, commonly called a “cell”, to progressively machine a part requiring several operations. CNC machines today are controlled directly from files created by CAD/CAM software packages, so that a part or assembly can go directly from design to manufacturing without the need of producing a paper drawing of the manufactured component. The CNC machines represent a special segment of industrial robot systems, as they are programmable to perform many kinds of machining operations within their designed physical limits. CNC machines are often run over night and over weekends without operator intervention. Error detection features have been developed, allowing CNC machines to telephone the operator if it detects an error such as a broken tool.
It is known to insert externally powered tools into a CNC machine spindle. An externally powered tool is inserted into the head of the CNC machine, with the CNC machine providing positional coordination of the externally powered tool for cutting or other purposes. The externally powered tool receives power from a source other than the rotation of the spindle of the CNC.
Externally powered tools, such as an air driven turbine put out an extremely high-speed rotation for rotating a cutting tool, which may be beyond the capability of the CNC machine spindle head. Further, the externally powered tool may expend less energy for rotation of cutter tool than the rotation of the entire CNC machine tool spindle.
What is needed in the art is an effective, easy to adjust speed regulation system for an air driven tool.